Intel Driver & Support Assistant CORS error / localhost 28387 not working – FIX

[Lol6]

Posting this here, because I really went through the ringer to solve this. 

Intel DSA kept getting hung on the scanning, and on a closer look, inspecting on dev tools I saw that it failed to connect in Edge, Firefox and Chrome. All local access allowed everything good.

Ok, I uninstalled, reinstalled. Nada.

I still ran into an issue where Intel Driver & Support Assistant would not work at all and showed:

• “Cross-Origin Request Blocked”
• or failed to connect to:

http://127.0.0.1:28387/intel/v1.0/ping

Symptoms

• DSAService shows as running
• But:

netstat -ano | findstr 28387

→ shows nothing (no LISTENING)

• Browser shows CORS error
• Scan never starts

So, I uninstalled Expressvpn... but unsuccessfully. So then I had to do it manually. It was so awful I don't think i'll install it ever again.

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Root cause (important)

The issue was caused by a leftover VPN network filter driver:

• ExpressVPN Packet Filter (expressvpn-pkf)
• Still attached to the Wi-Fi adapter even after uninstall

This filter interferes with localhost networking, preventing DSA from binding to port 28387.

---

How I diagnosed it

1. Checked port:

netstat -ano | findstr 28387

→ not listening

1. Checked adapter bindings:

Get-NetAdapterBinding -Name "Wi-Fi"

Found:

ExpressVPN Packet Filter → Enabled = True

Fix (what actually worked)

Step 1 – Disable the VPN filter binding

Disable-NetAdapterBinding -Name "Wi-Fi" -ComponentID expressvpn-pkf

Or via GUI:

• ncpa.cpl
• Wi-Fi → Properties
• Uncheck ExpressVPN Packet Filter

---

Step 2 – Reset network stack (if needed)

netsh winsock reset
netsh int ip reset

Step 3 – Restart adapter

• Disable / Enable Wi-Fi adapter

---

Step 4 – Verify

netstat -ano | findstr 28387

Now shows:

127.0.0.1:28387 LISTENING

DSA works immediately.

---

Important notes

• This issue is NOT actually CORS
• It is caused by network filter interference
• Reinstalling DSA alone does NOT fix it
• VPN uninstallers often leave behind bindings/drivers

---

Recommendation

If you use VPN software:

• Make sure it does NOT attach filters to your main adapter
• Or disable the binding manually

---

Summary

If Intel DSA runs but port 28387 is not listening, check for VPN filter bindings on your network adapter.

[Nikhil_Intel]

Hello Lol6,

Thank you for posting on the Intel Community Forum.

Thank you for taking the time to share such a detailed update and for walking us through your investigation and resolution.

I truly appreciate the effort you put into diagnosing the root cause and clearly documenting your findings.

Your analysis correctly highlights how leftover VPN network filter drivers specifically the Express VPN Packet Filter can interfere with localhost communication and prevent Intel Driver & Support Assistant from binding to the required port.

I am glad to hear that disabling the filter binding and resetting the network stack resolved the issue and that DSA is now working as expected. Your step‑by‑step breakdown and recommendations will be extremely helpful.

Thank you again for sharing your experience. Please don’t hesitate to reach out if you need any further assistance.

Best regards,

Nikhil

Intel Customer Support Technician